Additional Traction - at cross roads with options.

[weeds]

2000 defer, pre traction control, standard diffs

Car is being built up for an Overland trip, don’t want to chase hard tracks or bash and crash around 4WD parks, I just want to get to where I’m going easier without punishing the drive line.

Previous defer had front and rear ARB diff locks, worked perfectly, never forgot to engage, no issue with airlines, rear solenoid sucked small amount of oil back which was hardly an issue.

Looking at doing the rear diff first......as I hardly ever used the front locker on the tdi

Had the opportunity to follow a 130 with a Detroit fitted up Blue Rag......worked as it should, only thin I noticed was when turning on full lock on dirt the inside tyres skipping along, no different to the LSD on my hi-lux. I thought I was going to have trouble on Blue Rag but only had a bit of Wheel spin on the wombat holes on the last up before the main road.

Was always keen to install Ashcroft Air Locker this time around as I have onboard air and air lines don’t bother me and it’s hard to forget to engage when an something tough pops up.

The Detroit is now in the mix......

ATB......read a good explanation the other day on here and I’m sure it’ll probably be fine for a tourer.......although I do like 100% locked given I’m used to this with old defer

I like to support Aussie businesses so will more than likely go hi-tuff axle and drive flanges.

I haven’t really looked at the e-locker, it’s probably another option

So for a tourer that going to do the lap than be shipped overseas, actually the other way around......which way do I go.

[rangieman]

My choice is Ascroft air locker i just like the selectable choice [wink11]

[Bearman]

I would go a Trutrac or ATB in the front and Detroit no spin in the back.

[strangy]

You have already mentioned all the pros and cons etc.
I have Detroit "noSPIN" in mine and chose it for simplicity and function. Essentially fit and forget about it and maintenance really comes down to oil changes.
As you mentioned, no fuses, no wires, no relays, no switches, no air lines, no periodic or scheduled (unscheduled) disassembly for seals/orings. Suits me just fine.
Each has its merits for the individual user.
Lets assume whatever unit performs consistently as advertised, just get what you think will suit your preferred method/needs for activation.
IIRC yours will have the Rover diff?
Not sure if that changes the cost comparison.

[wdef34]

Friend, just get yourself an ARB on the rear sal(110 right?) and spend the extra cash in a pair of reinforced halfshafts and a twin air comp. In my opinion front locker is an overkill for overlanding. Also keep in mind ashcroft does not make anything for your rear diff. I have used aschroft atbs on rover diffs and they are very good though.
ps :arb is also Australian...

[weeds]

Friend, just get yourself an ARB on the rear sal(110 right?) and spend the extra cash in a pair of reinforced halfshafts and a twin air comp. In my opinion front locker is an overkill for overlanding. Also keep in mind ashcroft does not make anything for your rear diff. I have used aschroft atbs on rover diffs and they are very good though.
ps :arb is also Australian...

Didn’t realize Ashcroft don’t do sals......pretty sure I have a sals. Haven’t had a close.

Axle upgrade will be a given

Already have twin ARB compressor as I have air suspension.

Umm based on no Ashcroft for sals it might it might be down to

ARB or Detroit

[Bearman]

Given that choice I know which one I would go with!!

[uninformed]

Maxi drive is available for the Sals... maybe soon again for rover diffs

If P38 diff go the Ashcroft. It is a BETTER design than the ARB. The ARB is fine, but Ashcroft is BETTER.

Aussie yes, but they do partly off shore manufacturing...

Throw a Ashcroft ATB in the centre (LT230) and maybe front

+30% lower MD gearset :thumbsup:

[Bigbjorn]

I would go a Trutrac or ATB in the front and Detroit no spin in the back.

Me too. I have had Detroit Lockers in three vehicles, Dodge Challenger 600+ hp, Holden HT GTS350 with mods about 370 hp, and triple Detroits in a White Road Boss road train prime mover. All performed flawlessly other than the clanging noise on tight turns in the Dodge. In mud the White tended to want to go straight ahead no matter which way the steer wheels were pointing. Natural with 8 11.00 x 20s locked and pushing.

[Zeros]

Hey Weeds, you say the “Car is being built up for an Overland trip, don’t want to chase hard tracks or bash and crash around 4WD parks, I just want to get to where I’m going easier without punishing the drive line”. ...why do you need lockers?

You’ll be doing the vast majority of your big kms on bitumen and fast dirt. Over 20 years of these kinds of trips all over the continent I’ve never needed any extra traction aids over standard in my Defender. ...but if I was going to add something it would be Ashcroft ATB’s all the way, starting with the centre diff. ATB’s on fast dirt and wet roads will be working for you all the time. Simple, automatic and no locking required. They would give extra driveline all the time, but needless to say I’d only invest in them after making sure the radiator, water pump, alternator, bearings, etc are in as new condition.

Keeping it simple, focussing on the basics and lightening the load in every way possible is the key to successful trouble free overlanding imho.

[weeds]

Hey Weeds, you say the “Car is being built up for an Overland trip, don’t want to chase hard tracks or bash and crash around 4WD parks, I just want to get to where I’m going easier without punishing the drive line”. ...why do you need lockers?

You’ll be doing the vast majority of your big kms on bitumen and fast dirt. Over 20 years of these kinds of trips all over the continent I’ve never needed any extra traction aids over standard in my Defender. ...but if I was going to add something it would be Ashcroft ATB’s all the way, starting with the centre diff. ATB’s on fast dirt and wet roads will be working for you all the time. Simple, automatic and no locking required. They would give extra driveline all the time, but needless to say I’d only invest in them after making sure the radiator, water pump, alternator, bearings, etc are in as new condition.

Keeping it simple, focussing on the basics and lightening the load in every way possible is the key to successful trouble free overlanding imho.

Why, on the recent high country trip I lost traction once on blue Rag and I had hit two rocky step up with more speed than I liked, with my old defer I would have had rear locker engaged and would have crawled over both with out risking driveline and it would have been Moorhouse and enjoyable. Like I said getting to the destination easier.

I agree that I have rarely need traction aids when touring but if there is the slightest chance of loss of traction I used to engage my rear locker on my tdi.....wombat holes only get created by many cars loosing traction therefore I’m doing my bit to reduce track damage and and get there without any extra strain on the driveline. Many years ago I was on a trip with a mate, he had four attempted getting up a hill and need to flog his car, I crawled up with both lockers on (could have had a cup of tea in my hand) he went and got lockers installed the next week, being a mechanic he could see the value.

Re: centre diff when the transmission needs to be removed.

As I have a sals ATB is not and option for the rear.

Keeping it simple.....a traction aid can reduce damage to the vehicle or get one into more trouble but generally being able to slowly crawl over anything tough that presents. We are pretty good when packing but we don’t tough it anymore. Plus removing the few luxuries wouldn’t save enough weight to make one rock step on a super cool track up a mountain to get the views.

Leaning towards a Detroit, now to find pricing from a supplier and somebody to install.

Cheers everybody for your input.

[Bearman]

It's a pint of pee to install Weeds, I can talk you through that over the phone.

[martnH]

Hi weeds,
I am a theoretician (so correct me if I am wrong). I went to high country twice so I am not a completely newbie. I remember blue rag was easy when I was there the second time. The track was graded and they even removed the big rock near the top. Also Billy goat was heavily graded and pretty easy.

I prefer a full time 4wd compare to part time 4wd because of handling and safty. I think if your aim is to overland, safty and handling over long distance driving over various terrain is most important.

And for this reason, I don't like the Detroit no spin because it is an unlocker (axle is locked until you unlock it). To unlock the Detroit, you will need some differentiated torque between wheels and sometimes it is hard to achieve on a gravel/dirt/slippery terrain with limitrd traction. And if the Detroit is not unlocked, the truck will be dragging one wheel and turning circle increased. Afterall it is designed to go straight and straight only (and turn but only at tarmac). (I.e I don't think you can do U turn in the muddy paddock with a detroit no-spin hehe..Must be quite a scene to see one trying

And also for the same reason, I don't really like the limited slip (although I bought ashcroft ATB recently....). It is because the limited slip will send power to a wheel with least traction. And this will be unpredictable as you are not sure which side will get traction if you are pouncing around.also you are not sure if this power is continuous.(if a wheel lifted for a fraction of second, the torque bias will decrease significantly).

And here I will present a (rare?) situation where both no-spin and Lsd will make the vehicle unsafe and that is steep slippery downhill and with a crown slope (see the photo attached). In this case, it will be very hard for the truck equipped with no-spin or Lsd to go straight down the slope becusse of the way differential speed is managed. The truck is likely to move to one side of the slope.

And in such situation, the open diff (or a locker) will shine. With a locker, you can always disable the locking and return to open diff and all wheels on the truck will move freely this going down such a slope safely. It's like free flowing water, going to the lowest point.
That said, a long wheel base will negate some of such issues.

And finally, I have gone ashcroft ATB because my truck has traction control. I go this way because I acceptted the trade-off. But if I have plenty of money, I will go ashcroft air locker. Since your truck doesn't have traction control, I think a rear a locker will be the best option for overlanding.

P.s. I think TMJ prolocker is also pretty good.and ARB has changed its design so the seal is static now. I don't think any of them still made in Australia. Manufacturing moved to other country for $$$$$$$$$$$$

Cheers
Martinhttps://www.aulro.com/afvb/images/imported/2018/04/382.jpg

[martnH]

ATB in rover is equivalent to Truetrac in a Dana 60 Salisbury

[strangy]

It's a pint of pee to install Weeds, I can talk you through that over the phone.
^This.
Without starting a buy local debate: GBR supplied mine in 4 days to my door in Alice at almost $700 less than supply only local.
Even with pending GST changes its a tough argument.

[weeds]

Thanks for the detailed response martn.....

Umm, more to ponder

[Zeros]

Why, on the recent high country trip I lost traction once on blue Rag and I had hit two rocky step up with more speed than I liked, with my old defer I would have had rear locker engaged and would have crawled over both with out risking driveline and it would have been Moorhouse and enjoyable. Like I said getting to the destination easier.

I agree that I have rarely need traction aids when touring but if there is the slightest chance of loss of traction I used to engage my rear locker on my tdi.....wombat holes only get created by many cars loosing traction therefore I’m doing my bit to reduce track damage and and get there without any extra strain on the driveline. Many years ago I was on a trip with a mate, he had four attempted getting up a hill and need to flog his car, I crawled up with both lockers on (could have had a cup of tea in my hand) he went and got lockers installed the next week, being a mechanic he could see the value.

Re: centre diff when the transmission needs to be removed.

As I have a sals ATB is not and option for the rear.

Keeping it simple.....a traction aid can reduce damage to the vehicle or get one into more trouble but generally being able to slowly crawl over anything tough that presents. We are pretty good when packing but we don’t tough it anymore. Plus removing the few luxuries wouldn’t save enough weight to make one rock step on a super cool track up a mountain to get the views.

Leaning towards a Detroit, now to find pricing from a supplier and somebody to install.

Cheers everybody for your input.

Yes it comes down to the definition of overlanding vs hard tracks. Also where you’re planning to go.

....Maybe a centre ATB and rear locker is the go if your version of overlanding also includes hard tracks in the high country. 👍

[weeds]

Yes it comes down to the definition of overlanding vs hard tracks. Also where you’re planning to go.

....Maybe a centre ATB and rear locker is the go if your version of overlanding also includes hard tracks in the high country. [emoji106]

Yes what is the definition of over-landing/touring? Different for everybody.....I don’t chase hard tracks but they may pop up on journey....... It’d be a shame to be in the middle of Kazakhstan going somewhere awesome and open diffs with OEM axles prevents me, kinda log way to turn around.

If I go a selectable locker and it doesn’t get used at least I have confidence it’s there if needed.

If I go an unlocker I guess it’s in play all the time.

[Dorian]

Hi weeds,
I am ......

And also for the same reason, I don't really like the limited slip (although I bought ashcroft ATB recently....). It is because the limited slip will send power to a wheel with least traction. And this will be unpredictable as you are not sure which side will get traction if you are pouncing around.also you are not sure if this power is continuous.(if a wheel lifted for a fraction of second, the torque bias will decrease significantly).

... Cheers
Martin

perhaps just nit picking but an ATB is NOT a limited slip diff , provided that you have some resistance on the spinning wheel it will send the torque (hence power) to the slowest spinning (most traction) wheel. Granted a wheel in the air means it's the same as an open diff, but a bit of brake can fix this. (I've got traction control so other than when I had a play with some fuses out I don't have a huge amount of experience with it)

Mine has ATB's all round but the front went in about a 18 mths before the back, and then a year and a bit later the centre was done. I mainly do sand and gravel, the ATB in just the front made so much difference, TC light came on so much less, but that's all be said before.

I've only driven a Hilux with a rear detroit in it and then only for a few days but the change in steering in medium sand and dirt roads was not something I enjoyed but perhaps you'd get used to it. Soft and hard sand I hardly noticed any difference.

Regardless of the rear decision id be voteing for an ATB in the front.

[Slunnie]

I would fit the ARB diff locks. You know all of the advantages, they are 100% positive for when you're there to tour, are heavy and want NO fuss, they are open like a normal diffs when you don't want them so handling is always as expected, they are reliable and they are easy to get. They also don't need wheel spin to work which tears some tyres apart (ie lug removal). There is a lot of negative ARB, pro Ashcroft talk in LR circles, ARB is your option for the rear and I doubt very much that you will have any problems with either of them to be honest, but you like me have run them for a long time and have had good experiences with them, just about every other brand of 4WD that has a locker runs them and they are not so unique, especially with the update that has common parts. They're also made in Melbourne and the engineer is very easy to contact and a really great guy to chat with (in my case when investigating the build of hybrid lockers).

[martnH]

perhaps just nit picking but an ATB is NOT a limited slip diff , provided that you have some resistance on the spinning wheel it will send the torque (hence power) to the slowest spinning (most traction) wheel. Granted a wheel in the air means it's the same as an open diff, but a bit of brake can fix this. (I've got traction control so other than when I had a play with some fuses out I don't have a huge amount of experience with it)

Mine has ATB's all round but the front went in about a 18 mths before the back, and then a year and a bit later the centre was done. I mainly do sand and gravel, the ATB in just the front made so much difference, TC light came on so much less, but that's all be said before.

I've only driven a Hilux with a rear detroit in it and then only for a few days but the change in steering in medium sand and dirt roads was not something I enjoyed but perhaps you'd get used to it. Soft and hard sand I hardly noticed any difference.

Regardless of the rear decision id be vote for an ATB in the front.Thanks Dorian.

But still ATB is just one of the limited slip differentials.

The definition of Limited slip differentials is a device limiting maximum difference between two wheels

This includes torque sensing Lsd. And ATB is one of these. To be more exactly this category has two subgroups. One is helical gear Lsd (where ashcroft ATB sits). The other is cltuch type.

Also there is viscosmus Lsd. Which I think it's similar to a torque convertor that utilise the viscosity of heavy oil to limet the difference..

P.s.i think ATB is actuaually a commercial name registered by Quaife? Because the other helical gear Lsd are called torsen or Truetrac. Whatever the names is , these are gear driven lsds.

Cheers
Martin

[weeds]

Thanks Slunnie....

Just checking the Ashcroft website, it doesn’t appear they do an air locker for a Sals.

[Slunnie]

Also looked at a review of the Elocker by Stefan, really interesting and their locking mechanism allows them to unlock momentarily when changing wheel direction which I suspect may potentially lead to problems in the situation or later in the life of the locker. .

[weeds]

Also looked at a review of the Elocker by Stefan, really interesting and their locking mechanism allows them to unlock momentarily when changing wheel direction which I suspect may potentially lead to problems in the situation or later in the life of the locker. .

Interesting.....

[Slunnie]

Thanks Slunnie....

Just checking the Ashcroft website, it doesn’t appear they do an air locker for a Sals.

Simplifies the decision making. I'd keep whole system the same F&R with ARB, although I'm sure an Ascroft front would plumb straight in, but ARB F&R is just so simple to do and its all the same then.

[Slunnie]

Also looked at a review of the Elocker by Stefan, really interesting and their locking mechanism allows them to unlock momentarily when changing wheel direction which I suspect may potentially lead to problems in the situation or later in the life of the locker. .

Harrop Eaton E Locker vs ARB Air Locker vs TJM Pro Locker REVIEW [2018] | ALLOFFROAD #142 - YouTube (https://youtu.be/1nYZo--7Xh4)

[djam1]

I have a Td5 Defender with a rear ARB and a front Ashcroft ATB my previous V8 Stage 1 had a Detroit No Spin in the Salisbury.
The ATB is a good thing but its not a locker but it helps particularly with Traction Control more a comfort knowing that doesnt have a pathetic cross pin to break.
The ARB has been perfect no issues at all.
The Detroit No Spin was good but had its issues, they DO add additional backlash into the system people will be along to say this is not true if you read the documentation it will tell you that they do. Its not the crown wheel to pinion backlash but in the operation of the detroit itself.
A Detroit has peculiar effects on handling particularly when driving accross a sandy side slope this can be a pain driving along a beach.
Detroits occasionally will give an underwear changing bang when turning not a problem but scares you when it happens, many times I thought I had broken something but it never broke. The axles on the other hand needed to be heavy duty to cope.

I would have any of them but a controlled locker on the rear is a good thing, as is a Detroit the ATB on the rear not so much in my opinion.

Do you NEED to do anything to tour around Australia in a Defender No not in my opinion been doing it since the 1970s without the actual need for additional traction just drive accordingly.

[djam1]

Weeds
Off subject but buy yourself a reco kit for the ARB compressor if you are using it for the rear suspension
I find that they fail regularly
They are simple and cheap to rebuild but if you are not carrying parts it will become an issue

[Zeros]

Yes what is the definition of over-landing/touring? Different for everybody.....I don’t chase hard tracks but they may pop up on journey....... It’d be a shame to be in the middle of Kazakhstan going somewhere awesome and open diffs with OEM axles prevents me, kinda log way to turn around.

If I go a selectable locker and it doesn’t get used at least I have confidence it’s there if needed.

If I go an unlocker I guess it’s in play all the time.

Yes being prepared for every eventuality is tempting and deciding where to draw the line is as difficult as defining overlanding! 😇

Sometimes turning around is the best option too! But of course I get it...often you can’t!

Kazakhstan would be awesome overlanding. 🙂 I’d take my stock Defender there too.

All the good advice here so far suggests an ARB rear locker, Ashcroft ATB centre. 👍
Front? Meh, maybe that’s where the definition of overlanding ends and hard tracks begin? 😇

[rangieman]

Another positive on Slunnie`s point is with selectable you have the choice of engaging going down steep hills which i do often with the chance of lifting a rear wheel and loosing traction down hill [wink11]

[ozscott]

I would probably go a front first if coin is an issue and you are hill climbing. I still run just ETC and centre diff lock on my d2. I drove a hill with axle twisters recently in my D2 and then I drove my mates D2 (same line and crawl speed) that has Ashcroft ATB's front and rear and otherwise all same spec - both 5 speed V8's with very s imiliar lift and same spring type, shocks etc. His did it easier with no detectable spin. Having said that traction control assists greatly in locking up the ATB and it's a thing of beauty. He also went the Ashcroft HD rear axles and front half shafts and CV'S. Cheers

[tact]

Another positive on Slunnie`s point is with selectable you have the choice of engaging going down steep hills which i do often with the chance of lifting a rear wheel and loosing traction down hill [wink11]

The technique I use in that sutuation, with ATBs front and rear, is to preload the driveline a little by applying a little brake and driving through it (don't touch the clutch) when its likely to lift a wheel.

I do the same uphill too and manage to surprise myself how well the ATBs work in some pretty difficult situations.


BUT!....
If you are hitting really serious hard core situations, you'll need a fully locked diff, and HD half shafts, flanges, drive shafts etc. ATBs will just make you work too hard, and perhaps hammer the vehicle too hard in such extreme situations.


Different topic....
I have had the detroit style "unlocker" in a vehicle the past. With these units:
- when you are doing the office commute or school run on tarmac, at ANY time other than a dead straight section of road you are only driving one wheel, the inside wheel. (The outer is on overrun).
- often when on a straight section of road, after coming out of a bend in the road, you can still be driving just one wheel. The ratcheting mechanism in the diff linked to the previously outer wheel half shaft may be half a ratchet tooth ahead of being properly engaged even though turning at the same speed as the other side of the diff - its being driven by the roadwheel not the driveline.
- of course, when the (one) driven wheel gets driven to the point it loses its grip on the road surface, then the ratchet mechanism catches up with the lazy freewheeling wheel and it gets drive.
- this is where oft observed "handling oddities" comes from

Conversely, if on a soft or slippery surface where there is room for a lot of wheel slippage almost constantly (sand, mud, ice etc):
- in these circumstances the detroit "unlocker" will basically always be acting like a spool. (or like a selectable locker in locked mode)
- in some situations like this a "locked" diff is not the most effective option (e.g. slippery side slopes)
- unfortunately there is no "unlock" option with the detroit "unlocker" type system
- admittedly getting side-on traversing slippery side slopes are something we would all sensibly avoid.

[ozscott]

I haven't driven the ATB's on soft sand but I'm betty they are to the vehicles ability in those conditions. I also.read that they improve braking. Cheers

[rangieman]

The technique I use in that sutuation, with ATBs front and rear, is to preload the driveline a little by applying a little brake and driving through it (don't touch the clutch) when its likely to lift a wheel.

I do the same uphill too and manage to surprise myself how well the ATBs work in some pretty difficult situations.


BUT!....
If you are hitting really serious hard core situations, you'll need a fully locked diff, and HD half shafts, flanges, drive shafts etc. ATBs will just make you work too hard, and perhaps hammer the vehicle too hard in such extreme situations.


Different topic....
I have had the detroit style "unlocker" in a vehicle the past. With these units:
- when you are doing the office commute or school run on tarmac, at ANY time other than a dead straight section of road you are only driving one wheel, the inside wheel. (The outer is on overrun).
- often when on a straight section of road, after coming out of a bend in the road, you can still be driving just one wheel. The ratcheting mechanism in the diff linked to the previously outer wheel half shaft may be half a ratchet tooth ahead of being properly engaged even though turning at the same speed as the other side of the diff - its being driven by the roadwheel not the driveline.
- of course, when the (one) driven wheel gets driven to the point it loses its grip on the road surface, then the ratchet mechanism catches up with the lazy freewheeling wheel and it gets drive.
- this is where oft observed "handling oddities" comes from

Conversely, if on a soft or slippery surface where there is room for a lot of wheel slippage almost constantly (sand, mud, ice etc):
- in these circumstances the detroit "unlocker" will basically always be acting like a spool. (or like a selectable locker in locked mode)
- in some situations like this a "locked" diff is not the most effective option (e.g. slippery side slopes)
- unfortunately there is no "unlock" option with the detroit "unlocker" type system
- admittedly getting side-on traversing slippery side slopes are something we would all sensibly avoid.
In some down hill situations brakes are not advisable .
The way i drive is engine braking and foot brakes are a last resort and with that abs does not help in these situations [wink11]
Im like the majority with no ATB experience like ive said all along they all have their plus and negative`s .
I don`t get it why it is such a hard choice maybe for the newbie with no experience but for me it is selectable and no i have never had a compressor die when needed nor a air line or any other part of the locker and i have had ARB , and Ashcroft locker`s across 3 car`s over the year`s all with out issue .

[martnH]

Just to add to this database

The badass Pajero evo (Dakar all time record holder with 12 wins) has center open diff but front and rear torsen (another ATB) diffs.

Also the US military humvee has a similar setup. Open center and torsen front and rear

And this is the same setup I will get for my defender......

P.s. Prado, although I know not many of us acknowledge it's off-road capabilities, has torsen center diff. It is equivalent to the ashcroft ATB in a defender.


Cheers
Martin

[dero]

They all have pros & cons , for me it was simple is best , the detroit locker is probably the cheapest option , it is probably the strongest & most trouble free option , they are bullet proof and when you need it the most , it is right there , and the additional traction is about as good as it gets for most circumstances .
It was a chioce I made , and getting close to a million k's later , I still love it .

[ozscott]

In some down hill situations brakes are not advisable .
The way i drive is engine braking and foot brakes are a last resort and with that abs does not help in these situations [wink11]
Im like the majority with no ATB experience like ive said all along they all have their plus and negative`s .
I don`t get it why it is such a hard choice maybe for the newbie with no experience but for me it is selectable and no i have never had a compressor die when needed nor a air line or any other part of the locker and i have had ARB , and Ashcroft locker`s across 3 car`s over the year`s all with out issue .

It's not a simple choice even for experienced off-roaders. There is a sound reason why Dave Ashcroft sells so many ATBs. I would be in 2 minds and I have a bit of experience. It's not a simple choice for many. Some people find it a simple choice so more power to them hey.

Cheers

[rick130]

It's not a simple choice even for experienced off-roaders. There is a sound reason why Dave Ashcroft sells so many ATBs. I would be in 2 minds and I have a bit of experience. It's not a simple choice for many. Some people find it a simple choice so more power to them hey.

CheersDitto for my D2.

For what I do with it I think atb's all round are the best compromise and will probably be going that way.

I love selectable, but my thinking is that atb's plus the more aggressive tc that the CDL'less D2 appears to have will be 90-95% as capable as a fully locked set-up anyway.

Anyone that used to be on Outerlimits years ago might remember Sam Overton's 'Lockless' comp buggy?
Instead of being locked all round they fitted it with TruTracs and their own TC.
That thing was impressive!

[Zeros]

So...Overlanding has now become rock climbing and you need twin lockers and a whole new driveline HD everything? Ive been overlanding all over this continent in my stock Defenders for 20 years and never needed any lockers. I’ve towed Tojo’s, Nissan’s, Hiluxs out of many gnarly, rocky, hilly, boggy spots without issue. By all means get fully locked and loaded, but I’d be spending my money on a new radiator, new water and fuel pumps, filters, bearings and good tyres ...for Overlanding, which is generally understood as an extended journey.

[Zeros]

...as I said earlier. But felt I needed to reiterate. Overlanding is different to gnarly track conquering. Keeping it simple is the key to success.

[weeds]

So...Overlanding has now become rock climbing and you need twin lockers and a whole new driveline HD everything? Ive been overlanding all over this continent in my stock Defenders for 20 years and never needed any lockers. I’ve towed Tojo’s, Nissan’s, Hiluxs out of many gnarly, rocky, hilly, boggy spots without issue. By all means get fully locked and loaded, but I’d be spending my money on a new radiator, new water and fuel pumps, filters, bearings and good tyres ...for Overlanding, which is generally understood as an extended journey.

Maybe I shouldn’t have inserted overland!!! I also said I don’t chase hard tracks but you never know whats ahead on the track.

I have stated I just was to get there easier and not punish the driver it something pops up.

Are you saying you have never lost traction, had wheel slip or needed two goes?

In my 300 I didn’t as I alway engaged the rear locker (installed by previous owner who did a couple of laps of Aus) anytime I thought there was a chance of loosing traction even for a moment.

On my recent High Country Trip I would have preferred not to hit the two rocky loose steps as hard as I did as it was a little wild for 10m and I had a little bit of wheel spin returning from blue Rag, again in my old 300 I would have engaged the rear, the 130 in front had a Detroit and he just crawled over the wombat holes.

Out of interest what defer do you currently drive??

[Zeros]

Maybe I shouldn’t have inserted overland!!! I also said I don’t chase hard tracks but you never know whats ahead on the track.

I have stated I just was to get there easier and not punish the driver it something pops up.

Are you saying you have never lost traction, had wheel slip or needed two goes?

In my 300 I didn’t as I alway engaged the rear locker (installed by previous owner who did a couple of laps of Aus) anytime I thought there was a chance of loosing traction even for a moment.

On my recent High Country Trip I would have preferred not to hit the two rocky loose steps as hard as I did as it was a little wild for 10m and I had a little bit of wheel spin returning from blue Rag, again in my old 300 I would have engaged the rear, the 130 in front had a Detroit and he just crawled over the wombat holes.

Out of interest what defer do you currently drive??

Honestly and all jokes aside, if I was on an extended overland trip I would be avoiding climbing 10m rock steps, because in the scheme of things attaining that summit would be a low % gain and a risk to the far bigger goal of a trouble free extended journey. Being stuck in a remote place on a long journey because I broke something would not be much fun. I’d avoid the rock step climb in favour of the longer goal.

No limits belongs to weekend rock scrambling tonka trucks. Overlanding is about simplicity, long term durability and safety. But that’s just my view.

Defender Puma 2014 & Defender Tdi 1998. Both brilliant in their own way.

I am looking at getting an Ashcroft centre ATB in the Puma for durability as the newer transfer cases are less robust. It would also improve fast dirt dynamics. Perhaps a rear as well one day, but budget is limited and there are many other priorities. I just don’t really need lockers.

...by the way, I’ve never needed a winch either. If I can’t get through without one I won’t go there. Although it’s actually never stopped me going anywhere I wanted to go and that includes river crossings over the bonnet and plenty of deep mud that others needed towing or winching out of. Its all about the line, the speed, gear selection, anticipation, walking the crossing, stopping for a cuppa and recognising the various limitations - risk vs reward.pa

Stock Defenders are awesome. Nothing else comes close.

[ozscott]

Another advantage of ATB is where you have tight turns or side slopes. They allow tighter turns than lockers and don't tend to throw sideways. It's a fantastic point and shoot. In the extremes of say climbing tall rock steps one after another with twists then sure then full locker would remain king but for everything else the ATBs would be better in my view and always 'on'. Cheers

[weeds]

Let’s re-focus.......

ATB’s are not available for a sals, I put a cross through that option days ago

I was leaning leaning toward a Detroit but after reading some awesome posts on here and talking to an owner of a Detroit I’ve decided it’s not for me.

TJM Pro Locker doesn’t appear to be an option....didn’t check if the e-locker was available for a sals

I’ve decided on an ARB for the rear.....had one on my previous defer, worked as it should, selectable and I already have onboard air. Will get some pricing over the next week or so.

If I progress to the front I think I’m thinking ATB as I didn’t really like the ARB in the front of the dirty old tdi ....but it’s way down on the list.

Thanks heaps to all the helpful and informative posts, I’m certainly a lot wiser now.

Cheers

[weeds]

Weeds
Off subject but buy yourself a reco kit for the ARB compressor if you are using it for the rear suspension
I find that they fail regularly
They are simple and cheap to rebuild but if you are not carrying parts it will become an issue

Umm, we use ARB compressors at work an I’m not aware of any failures. I have a twin mounted and have considered throwing the single portable in but space is at a premium.

[djam1]

I have had 4 failures 2x broken crank bolts, a failed valve plate and a failed thermal switch.
Very cheap to fix all of them but one incident was coming off an aboriginal community in the Kimberly and left me in a bind fortunately I had the air locker compressor that saved the day.
I now have 3 located in different locations feeding.a tank that way I have no issues just rebuild for $40 when it stuffs up

I use the compressor for rear firestone airbags (not full air) pumping tyres and the locker

I run the air tank at 150 PSI this maybe why I have issues

[Slunnie]

Let’s re-focus.......

ATB’s are not available for a sals, I put a cross through that option days ago

I was leaning leaning toward a Detroit but after reading some awesome posts on here and talking to an owner of a Detroit I’ve decided it’s not for me.

TJM Pro Locker doesn’t appear to be an option....didn’t check if the e-locker was available for a sals

I’ve decided on an ARB for the rear.....had one on my previous defer, worked as it should, selectable and I already have onboard air. Will get some pricing over the next week or so.

If I progress to the front I think I’m thinking ATB as I didn’t really like the ARB in the front of the dirty old tdi ....but it’s way down on the list.

Thanks heaps to all the helpful and informative posts, I’m certainly a lot wiser now.

Cheers

Something worth considering... a ATB requires wheel spin to work and if you have a locker at the rear it will mean that to make the ATB work you will have to spin both rear wheels which will make the rear slide sideways on the track. I tend that think thats the situation that makes you pull the winch more often than anything else when you've just wedged the vehcile against the side of the track and you haven't got enough traction. I would recommend that you either run ATB F&R or run lockers F&R. My opinion is to not mix them.

[Slunnie]

Re the air compressors, when I had the old type it threw the conrod, but the I've had the new type for about 8 years now and so far so good. Prob 150psi is a bit (lot!) too much, ARB set them up for 100psi max. :lol2:

[weeds]

Something worth considering... a ATB requires wheel spin to work and if you have a locker at the rear it will mean that to make the ATB work you will have to spin both rear wheels which will make the rear slide sideways on the track. I tend that think thats the situation that makes you pull the winch more often than anything else when you've just wedged the vehcile against the side of the track and you haven't got enough traction. I would recommend that you either run ATB F&R or run lockers F&R. My opinion is to not mix them.

I don’t quite follow....how does an ATB in the front rely/work with the locked rear?

[djam1]

Re the air compressors, when I had the old type it threw the conrod, but the I've had the new type for about 8 years now and so far so good. Prob 150psi is a bit (lot!) too much, ARB set them up for 100psi max. :lol2:

Sorry it is 120 PSI with the relief valve in the compressor factory set at 150 PSI

[Ranga]

I think we all need to remember to stay on topic - this is about options for Weeds' vehicle, not a general locker debate. H's already mentioned that ATB isn't an option, and he's already decided on locking the rear salisbury.

I recently had the pleasure of following Weeds through the Vic High Country, and my Detroit had had a very easy life. That is until we hit Blue Rag, and understandably he suggested I go first due to me having the lockers, and both of us not knowing what was ahead of us. In the end, I was very impressed with how easily (and slowly) the Detroit got us to the top, even in a heavy 130 at max GVM.

Whilst not an essential side-track, it was a fantastic experience, and to me an example of what overlanding is all about - experiencing sights. We certainly didn't need to do that track, but I'm damn glad we could and did. I imagine some may argue you could also see a lot of the world with only a 2WD, but imagine all the sights you would have to miss out on, simply because a 4WD was necessary, or maybe only even preferable. Hence, whilst it might be true that a rear locker isn't necessary, I personally believe a rear locker is certainly preferential... at least to me! I can only imagine the feeling sitting at the bottom of Blue Rag, and deciding to miss out because I didn't have the belief in my vehicle (or skills!).

I was happy to admit to Weeds that I'm unsure a Detroit is the best option. It suited me at the time of choosing - under $1000 fitted seemed like great value, and all the research I did suggested it was a sound option. I've never has any other locker, and can definitely see the pros and cons in each. Personally, if I didn't have a Detroit, I'd have an ARB. A major factor being that they are very common and widely distributed, with a pretty good reputation. As much as I love how the Detroit is always already engaged when you need it, a being able to turn a selectable locker on and off is a good thing I reckon.

Anyway, I'm enjoying the on-topic replies, so keep them coming!

[Slunnie]

I don’t quite follow....how does an ATB in the front rely/work with the locked rear?

When in 4WD, the front and rear propshafts are forced to rotate at the same speed, so the average speed of the front and rear axles are forced to be the same. (Lets say 10kmh front and rear axle speed))

The rear being locked means that both wheels are also forced to spin at the same speed (with 10kmh axles speed, both RL and RR wheels are forced to spin at 10km/h)

The front having an ATB means that there is unlocked diff action and either the front wheels are travelling at the same speed (ie the ATB is inactive so RL/RR@10kmh, FL@10kmh and FR@10kmh ) or the front wheels are spinning at different speeds (eg RL/RR@10kmh, FL@7.5kmh, FR@12.5km when you're on a dodgy track but still moving although both rears are still spinning faster than ground speed, or more to the point RL/RR@10km/h, FL@20km, FR@0kmh when you're on a dodgy track, not moving anymore and the ATB disengages because it has no torque to bias across).

The ATB works by torque biasing. Torque bias, is the value of torque the wheel with more traction gets compared to the wheel with less traction. With a Ashcroft ATB this is 3:1, Eaton Detroit Trutrac 3.5:1 and Quaife I believe is 4:1, so if you do got this way, at least look at the Detroit Trutrac (known as "TT", the Quaife is expensive and iirc runs a funny spline halfshaft. Never the less you can see that by design, these diffs are much better suited to road and rally race cars on race tracks rather than 4WD's or in 4WD's to those with ETC, but I still don't think they are at all comparable to the positiveness of locking diffs. If you do want ATB front and rear I believe you can get the TT for Rover and Salisbury axles - edit, sorry, I think this is for the 4.7 Salisbury..

Just press the front locker button on the dash and it just works 100% when you want.

[tact]

In some down hill situations brakes are not advisable .
The way i drive is engine braking and foot brakes are a last resort and with that abs does not help in these situations [wink11]
[...]

What situations are you thinking of? (Regards, "...some down hill situations brakes are not advisable")

In the situation I described - steep downhill, light braking intended to load the driveline a little in case a wheel lifts - the driveline is fully engaged, engine braking is still in play and overcoming the light braking forces, centre diff locked of course. The trailing braking just ensuring no upset should a wheel lift. Always a good outcome with this.

(Taking it to extremes... if one had to come to a complete stop on a steep downhill its safest to brake til engine stalls. No use of clutch, no disengaging the transmission.)

Of course if no risk of lifting a wheel - just let engine braking do its thing. (I don't have ABS in any case - so its no help to me.) :)

Certainly any action that disengages the driveline, in the scenario I describe, is outright dangerous (things like pressing the clutch pedal, as mentioned in my post)

[tact]

Something worth considering... a ATB requires wheel spin to work [...]

Absolutely not true! Please!

The best way to think of an ATB is:
- Its an open diff that just doesn't do the differentiation bit very well (unless one side of it is completely unloaded).
- And the more "weight" on the drive line (the more torque applied) the "worse" an ATB will be at allowing differentiation. Even before there is any difference in shaft/wheel rotational speeds across it.
- i.e. it is actually passively resisting differentiation while you drive a straight line, BEFORE you even ask it to differentiate. BEFORE any wheel loses its grip on the trail. i.e. Preemptive!

What you may have been thinking of is that, as (preemptively resisted) differentiation occurs (often a VERY good thing denied by a full locker) - the helical gears in some ATB designs like the Ashcrofts and Truetracs get driven harder into the ends of their carrier pockets and that increased friction INCREASES the torque bias ratio a little.

An ATB doesn't need any rotational difference (e.g. wheel spin as asserted in the quote above) across it to work. It needs load on the driveline (torque applied). The more torque applied, the more it will resist differentiation. Before you even ask it to differentiate, before any wheel spin occurs.

To bring this back to the OP's questions - now myths about ATB's are hopefully dispersed:
- good move going to a full air locker in the Sals rear. Even if there were an ATB option, your clarified use cases would need to have a fully locked rear axle at times and an ATB can never deliver that. (ATB combined with traction control would come close but wouldn't be my choice. Am rather glad my Malaysian spec 2013 TDCi doesn't have TC)

- An ATB may be a good choice in the front. But if the use cases you have in mind would mean a full locker is needed in the rear then I'd be thinking you wouldn't want to be farting about with left foot braking to control a loose front end either. Go full locker in the front too!

[tact]

Another advantage of ATB is where you have tight turns or side slopes. They allow tighter turns than lockers and don't tend to throw sideways. It's a fantastic point and shoot. In the extremes of say climbing tall rock steps one after another with twists then sure then full locker would remain king but for everything else the ATBs would be better in my view and always 'on'. Cheers

Absolutely right there ozscott.

I am reminded of the early adverts for anti skid braking: Car on wet slippery road surface, an obstacle suddenly appears, panic braking, not going to stop in time in a straight line, but with ABS can be hard on the brakes and still steer a safe line around the obstacle despite the slippery surface.

ATB's are NOT a replacement for ABS by any standard (my 2013 TDCi doesn't have ABS or TC) - but they have a similar effect (being able to have effective steering inputs in difficult situations) like slippery braking and steep descents. They behave the same whether under engine braking, or engine driving (e.g. driving up slippery slopes, side slopes etc).

Its not the OP's use case - but for anyone else not needing full locked diffs at times (even it if is just the 5 minutes needed to get to the top of a serious rock step a few times a year) - ATBs present a lot of benefit for the other half million hours in a year.

[tact]

I don’t quite follow....how does an ATB in the front rely/work with the locked rear?

In short it doesn't. Some real misconceptions in some comments being offered about ATB's. There would be no issue with having ATB's in front axle, or centre diff, or both - with a full locker or detroit (un)locker in the rear. No negatives. some definite advantages.

But as just posted in a previous note here... If you are in a seriously tough climb, implying lots of wheel spin going on, wheels in the air etc - you'd be WAY better off trading-off some of the ability to steer and going for a full locker in the front as well as rear

With an ATB in the front, on a serious hard climb, you don't want to have to deal with lots of front wheel spin. (which reduces ATB effectiveness btw, its not "needed to make the ATB work" as has been asserted). Even if you have traction control to brake spinning wheels for you, the TC still allows some wheel slip (it needs it to work!) and a full locker would just make life in that circumstance so much easier.

[Slunnie]

Absolutely not true! Please!

The best way to think of an ATB is:
- Its an open diff that just doesn't do the differentiation bit very well (unless one side of it is completely unloaded).
- And the more "weight" on the drive line (the more torque applied) the "worse" an ATB will be at allowing differentiation. Even before there is any difference in shaft/wheel rotational speeds across it.
- i.e. it is actually passively resisting differentiation while you drive a straight line, BEFORE you even ask it to differentiate. BEFORE any wheel loses its grip on the trail. i.e. Preemptive!

What you may have been thinking of is that, as (preemptively resisted) differentiation occurs (often a VERY good thing denied by a full locker) - the helical gears in some ATB designs like the Ashcrofts and Truetracs get driven harder into the ends of their carrier pockets and that increased friction INCREASES the torque bias ratio a little.

An ATB doesn't need any rotational difference (e.g. wheel spin as asserted in the quote above) across it to work. It needs load on the driveline (torque applied). The more torque applied, the more it will resist differentiation. Before you even ask it to differentiate, before any wheel spin occurs.

To bring this back to the OP's questions - now myths about ATB's are hopefully dispersed:
- good move going to a full air locker in the Sals rear. Even if there were an ATB option, your clarified use cases would need to have a fully locked rear axle at times and an ATB can never deliver that. (ATB combined with traction control would come close but wouldn't be my choice. Am rather glad my Malaysian spec 2013 TDCi doesn't have TC)

- An ATB may be a good choice in the front. But if the use cases you have in mind would mean a full locker is needed in the rear then I'd be thinking you wouldn't want to be farting about with left foot braking to control a loose front end either. Go full locker in the front too!

Of course it does require wheel spin or on the road differences in wheel speed, otherwise you can't have torque differences on a differentiating diff.

Do you disagree with these quotes?

This is from Eaton, manufacturer of the Detroit TT

The Truetrac operates as a standard or open differential under normal driving conditions, allowing one wheel to spin faster or slower as necessary. When a wheel encounters a loss of traction or the terrain changes, the gear separation forces take effect and transfer torque to the high-traction wheel. The helical-shaped gears mesh with increasing force until wheel spin is slowed or completely stopped. When the vehicle exits the low traction situation, the differential resumes normal operation.

This is from Ashcroft transmissions


The Limited Slip operation differs from the Locking differential in that it is never 100% locked. It operates by applying torque to the wheel with traction when the other wheel looses grip.
The ATB gear type limited slip relies on the internal friction generated by gear sets within the diff centre, these gear sets are unsupported and designed to be ineffecient. In a normal situation, i.e. on road this diff will be totally transparent, you will not know it is fitted. Provided both wheels have grip no torque biasing takes place, on a bend or corner the faster outer wheel will try to bind up the internal gears but the inner slower wheel constantly unwinds the gears, so again on a corner no bias is felt. On low or no traction surfaces where one wheel has considerably less traction than the other and thus tends to spin, the gear action within the diff causes friction which in turn applies load to the wheel with traction. The amount of torque applied depends on what is termed the 'Bias ratio'. Bias ratios can be varied by different pre-loads and different gear profiles but the most common have a bias ratio of approx 2:1.

The advantage of a Limited Slip differential is that it is totally automatic, no driver interaction and retains drive to both wheels at all times.

The disadvantage of ATB is that if one wheel is totally off the ground ,i.e. no drive then the other wheel similarly because the bias ratio is still 2:1 i.e. 2 x nothing is still nothing. Attempts at changing the preload or left foot braking can then fool the ATB into working or better still if the vehicle is fitted with ATC (automatic traction control) the ATB will enhance the action.

and this is from Quaife


Once installed, drivers will notice an immediate difference, as the Quaife (ATB) limited slip differential automatically biases the torque across the axle to the wheel with the most grip. Unwanted wheelspin and slip are greatly reduced, resulting in <snip>

Silent in operation (even during low-speed parking manoeuvres) the Quaife ATB limited slip unit never ‘locks,’ making it progressive, <snip>

[Slunnie]

In short it doesn't. Some real misconceptions in some comments being offered about ATB's. There would be no issue with having ATB's in front axle, or centre diff, or both - with a full locker or detroit (un)locker in the rear. No negatives. some definite advantages.

But as just posted in a previous note here... If you are in a seriously tough climb, implying lots of wheel spin going on, wheels in the air etc - you'd be WAY better off trading-off some of the ability to steer and going for a full locker in the front as well as rear

With an ATB in the front, on a serious hard climb, you don't want to have to deal with lots of front wheel spin. (which reduces ATB effectiveness btw, its not "needed to make the ATB work" as has been asserted). Even if you have traction control to brake spinning wheels for you, the TC still allows some wheel slip (it needs it to work!) and a full locker would just make life in that circumstance so much easier.
I've outlined pretty clearly the issues with running a rear locked diff with an ATB front in situations where both diffs are being drawn upon and the problem of differing wheel speeds

[Zeros]

Its not the OP's use case - but for anyone else not needing full locked diffs at times (even it if is just the 5 minutes needed to get to the top of a serious rock step a few times a year) - ATBs present a lot of benefit for the other half million hours in a year.

...which is why I think ATB’s are better for long distance overlanding if you think I you need extra traction...it’s constant as so well described Tact. ...or in the OP’s case with a sals rear diff - locker rear / ATB centre.

[AK83]

When in 4WD, the front and rear propshafts are forced to rotate at the same speed, so the average speed of the front and rear axles are forced to be the same. (Lets say 10kmh front and rear axle speed))

The rear being locked means that both wheels are also forced to spin at the same speed (with 10kmh axles speed, both RL and RR wheels are forced to spin at 10km/h)

.....

Trying to get my head around a real world situation as described here:

that is for the rears to have to rotate at 10k/h, and therefore force the unloaded front wheel to rotate at 10k/h, the implication here is that both rear wheels are spinning at 10k/h(obvious I know).
But in what situation would you find that the rears are spinning at 10k/h and the car not moving forward by any amount?

For the front ATB to stop working in such a situation would imply that both rear wheels are off the ground and spinning at 10k/h AND the car is not moving forward. ie. you're hung up on the chassis with the air under both rear wheels.

That's a fairly extreme off road situation!

As long as some momentum is maintained, and there is a small amount of load on both of the ATB driven wheels, it doesn't actually spin. As it tries too the other wheel takes up the torque immediately.

The term spin with an ATB is referring to the relative spin .. that is how much spin one wheel has relative to the other on the ATB driven axle .. it's not actually spin.

So back to the situation described above:

If the rears are in the air, and one of the front wheels needs to spin at 10k/h, that also means that this front wheel has to also be in the air for it to actually spin.

If you have three wheels in the air, CDL locked, using full lockers on both axles, and only one wheel capable of driving the vehicle, you then have all the torque of the engine driving that one front wheel.
The two scenarios most likely to occur are that the wheel with grip will most likely spin as it probably hasn't got enough friction to pull the 2T weight of the vehicle, or if it did, you most likely break an axle or CV having all the tractive effort on just that one wheel trying to pull the vehicle out.

Either way that's some pretty extreme off roading.

[dero]

If this requires a new thread , please advise .
With regard to the tendency of a locked rear diff to make the rear of the vehicle slide down hill , ie sloping beach etc.
I have had this happen in the real world , but did not connect it with a locked rear . Could one of you learned gentlemen please explain why this happens .

[AK83]

....
I have had this happen in the real world , but did not connect it with a locked rear . Could one of you learned gentlemen please explain why this happens .

happens with LSDs too.

Easy way to imagine it and why.

imagine a 2WD car with a LSD/Locker/ATB/Torsen diff, where on full power both rear wheels spin. Almost all will have a tendency to slip sidways at the rear as the rear wheels fight the spin to find grip.
Very few don't slip sideways, and usually those that don't have really well sorted suspensions.
But even perfectly sorted suspensions will still slip sideways with rears spinning(eg. racing cars, V8 Supercars, F1, etc.) as they light up the rears when they line up on the grid to warm the rears up .. etc. etc.

Same thign happens in off road. A side sloping track both rears locked so they don't slip relative to each other .. etc. if they just slip a little bit(due to low friction surface) they'll slip sideways with the grade of the slope.

I used to drive an old Frontera, had open front and LSD rear .. terrible off roader, but had 4WD all the same. Was ok on sand, but I think only due to the 10.5" tyres I had fitted, and it's rear LSD.
On side slopes it also used to slide sideways if the ground was of the low friction type(sand, very loose gravel, etc).

If only the one wheel spun in the above situation, ie. the diff unlocked, or open as normal, then that means the other didn't spin. The non spinning wheel provides the lateral stability that minimises or eliminates sideways stepping.

[Slunnie]

Trying to get my head around a real world situation as described here:

that is for the rears to have to rotate at 10k/h, and therefore force the unloaded front wheel to rotate at 10k/h, the implication here is that both rear wheels are spinning at 10k/h(obvious I know).
But in what situation would you find that the rears are spinning at 10k/h and the car not moving forward by any amount?

For the front ATB to stop working in such a situation would imply that both rear wheels are off the ground and spinning at 10k/h AND the car is not moving forward. ie. you're hung up on the chassis with the air under both rear wheels.

That's a fairly extreme off road situation!

As long as some momentum is maintained, and there is a small amount of load on both of the ATB driven wheels, it doesn't actually spin. As it tries too the other wheel takes up the torque immediately.

The term spin with an ATB is referring to the relative spin .. that is how much spin one wheel has relative to the other on the ATB driven axle .. it's not actually spin.

So back to the situation described above:

If the rears are in the air, and one of the front wheels needs to spin at 10k/h, that also means that this front wheel has to also be in the air for it to actually spin.

If you have three wheels in the air, CDL locked, using full lockers on both axles, and only one wheel capable of driving the vehicle, you then have all the torque of the engine driving that one front wheel.
The two scenarios most likely to occur are that the wheel with grip will most likely spin as it probably hasn't got enough friction to pull the 2T weight of the vehicle, or if it did, you most likely break an axle or CV having all the tractive effort on just that one wheel trying to pull the vehicle out.

Either way that's some pretty extreme off roading.
If you had locked rears spinning at 10kmh and the the ground speed was 0kmh you would probably have one front at 0kmh and one front at 20kmh.

Lots of scenarios where this happens, seemingly every time I get stuck! :lol2: Anything from catching a diff on a rock, steps in a track especially if the step is one side or at an angle or big or there is a lot of load on the vehicle, low traction surfaces where there isn't enough traction to drive be that mud, loose rocks, soil and notably clay, climbing with cross axling with low traction etc. The rear wheels are not normally off the ground... normally, just loss of traction. Just takes a wet day on your holiday.

Your analysis of driveline failure and traction etc is really good! I remember doing the sums years ago and seeing that the engine and gearbox does produce enough torque to break an axle at will, and you're right also in that the torque limiting factor was traction. I remember also a reply by one of Australias best known rocke buggy builders to a comment that a particular driveline was indestructable, and replied that he could break it, just bind up a wheel in something and drive it. :eek2:

[DeeJay]

Interesting comments.
My pennyworth is, like others have said they have fitted, I have a Detroit Locker ( not to be confused with TruTrac) in the rear Salisbury & an Ashcroft ATB in the front. I think in the 3 years of usage they have done the Simpson Desert, Coorong sand travel, Billy Goat & Blue Rag a few times, Mt Pinnibar, - at least a dozen Vic High Plains trips plus numerous interstate trips etc etc.
Previous Land Rovers I've had have, had - ARB lockers Rear & later F&R - Maxidrive F& R & McNamara rear Rover locker.
Basically I fitted the Detroit Locker as an experiment, thinking it would be easy to remove & sell if I wasn't happy with it.
I won't be spending the money to upgrade to a lockable rear.
Whilst I'm not perfectly happy with the Detroit Locker ( uneven rear tyre wear & occasional clunk & Kangaroo hop) my decision to fit it was primarily based on cost & on that basis I won't be justified going to a full locker again.
However, If I win Tatts I would probably go selectable locker in the rear - sorry not ARB..... and leave the ATB in the front, All I can say is, with my current setup, I have easily driven up/ through obstacles that have taken vehicles in front of me a lot of trouble to negotiate.

Of course Tyres & tyre pressures are an equally important factor in traction.
David

[tact]

Of course it does require wheel spin or on the road differences in wheel speed, otherwise you can't have torque differences on a differentiating diff.

Do you disagree with these quotes?

This is from Eaton, manufacturer of the Detroit TT


This is from Ashcroft transmissions



and this is from Quaife

Some of what you quoted is quite accurate (and does not contradict what I have written). Some is classic marketing spin, dumbing things down for people not up to the real detail:
- “it’s like an open diff that’s not very good (at being open)” isn’t a good sales pitch.
- comments like “when a wheel spins the ATB delivers more torque to the other wheel” is much easier to understand even if not the whole truth. And such a comment:
- does not contradict what I wrote (I wrote that when wheel spin does occur more biassing happens).
- does not say that wheel spin is “needed” for an ATB to work.

Go go have a read at the torsen site. Torsen(R) Traction (https://torsen.com/how-it-works/)

It gives a more technically accurate description.

[tact]

If this requires a new thread , please advise .
With regard to the tendency of a locked rear diff to make the rear of the vehicle slide down hill , ie sloping beach etc.
I have had this happen in the real world , but did not connect it with a locked rear . Could one of you learned gentlemen please explain why this happens .

In any situation except flat level absolutely straight line travel (assuming all tyres exactly the same circumference - not usually the case, manufacturing tolerances and wear etc) - just having a lockable diff locked will be forcing one of the wheels on an axle to scuff. I.e. breaking traction. Even if that’s measured in just millimetres... it’s still a forced breaking of traction, slippage, on one or the other tyre, for every centimetre the wheel rotates.

Tilt the surface and reduce the surface friction available (mud, wet grass, sand) and gravity assist exacerbates the tendency for that slippage to be in the down slope direction.

[izu]

When turning the inside rear wheel is the slowest so you get wheel spin on that wheel because it is fighting the front diff

[bachir51]

Didn’t realize Ashcroft don’t do sals......pretty sure I have a sals. Haven’t had a close.

Axle upgrade will be a given

Already have twin ARB compressor as I have air suspension.

Umm based on no Ashcroft for sals it might it might be down to

ARB or Detroit

Check out if ashcroft don't do for rover. I have had issues with ARB. They just don't want to see you if you have a problem. TJM are also Australian and good customer service.

[weeds]

Check out if ashcroft don't do for rover. I have had issues with ARB. They just don't want to see you if you have a problem. TJM are also Australian and good customer service.

Ashcroft replied to my email confirming they don’t do Salisbury diffs.....

TJM website doesn’t show an option for Salisbury.

Think I mentioned earlier that my previous defer had front and rear ARB Diff Locks for 15+ years and I never had one issue over the 10 years that I owned it. Yeah the rear sucked the smallest amount of oil back when disengaging , no biggie and didn’t affect operation plus they are changed the design.

I’ve had plenty of other issues with my defers but I keep purchasing.

[SSmith]

Ashcroft replied to my email confirming they don’t do Salisbury diffs.....

TJM website doesn’t show an option for Salisbury.

TJM website is not very user friendly. But they do exist - I have purchased and installed one into a friends 200tdi defender.

[weeds]

TJM website is not very user friendly. But they do exist - I have purchased and installed one into a friends 200tdi defender.

Thanks for the heads up...

E-locker or Pro-locker?

I’m not interested in the e-locker

[weeds]

Just rang TJM and they do a pro locker for the sals.....

400 More than ARB and that’s with me finishing off the install.

[SSmith]

Just rang TJM and they do a pro locker for the sals.....

400 More than ARB and that’s with me finishing off the install.Sry for the slow reply.

Yes, Pro locker.

IMHO it is worth extra $$

He has not had any issues with air leaks,etc. But IF it does happen the actuator is seperate to the diff core. So its as simple as remove the diff cover, remove the acutator, fix/replace and reassemble.

[weeds]

Sry for the slow reply.

Yes, Pro locker.

IMHO it is worth extra $$

He has not had any issues with air leaks,etc. But IF it does happen the actuator is seperate to the diff core. So its as simple as remove the diff cover, remove the acutator, fix/replace and reassemble.

Cheers and thanks for the explanation of the actuator.

Without sounding like a cracked record my previous lockers did 300000km with out issue and I engaged the rear every single time I thought there was chance of a wheel loosing traction, even the smallest slip.

ARB it will be.

[martnH]

TJM website is not very user friendly. But they do exist - I have purchased and installed one into a friends 200tdi defender.The lattest updated ARB lock also has static seal. The previous, the seal will wear and eventually leak. I think that the main reason for the name ARB leaker

Do you know the structural difference between ARB, TJM prolocker and ashcroft?


Cheers
Martin

[weeds]

The lattest updated ARB lock also has static seal. The previous, the seal will wear and eventually leak. I think that the main reason for the name ARB leaker

Do you know the structural difference between ARB, TJM prolocker and ashcroft?


Cheers
Martin

Yes read about the updated seal although mine never leaked

Nope don’t really know in and outs of the differences between them TJM and ARB. Ashcroft don’t do sals so not much point looking into the internals.

[SSmith]

Do you know the structural difference between ARB, TJM prolocker and ashcroft?

No.

[weeds]

I was speaking to a guy at Cooma who has front and rear diffs with maxidrives fitted....his sons not keen in swapping them into his rangie....maybe I make an approach, would mean giving up the sals

[crump]

dunno if they still do them, but you could just go with reduction gears from MR. Still in mine, still going fine, and for general buggering about never needed lockers and never broke anything.

[weeds]

dunno if they still do them, but you could just go with reduction gears from MR. Still in mine, still going fine, and for general buggering about never needed lockers and never broke anything.

Bloody hell, where have you been of late

[rick130]

The TJM ProLocker is a Jac Mac made under license, they should be bullet proof.

[uninformed]

I was speaking to a guy at Cooma who has front and rear diffs with maxidrives fitted....his sons not keen in swapping them into his rangie....maybe I make an approach, would mean giving up the sals


Ill be swapping my Maxid drive locked Sals for a built MD Rover rear diff in my 110. No hesitation

[Slunnie]

The TJM ProLocker is a Jac Mac made under license, they should be bullet proof.

Are the materials and any treatment the same also?

[rick130]

Are the materials and any treatment the same also?I have no idea, nor know where TJM are making/getting them made.

[Dervish]

Do Jac Mac still do their hypoid locker? That would be my choice for a front, provided it doesn't cost a mint.

[rangieman]

Do Jac Mac still do their hypoid locker? That would be my choice for a front, provided it doesn't cost a mint.
Id rather deal with TJM than Jac Mac any day [wink11].
His products are first class but his personality is a little different at times to say the least:cool:

[86mud]

Hi Weeds

I've had ARB air lockers in my 130 for 9 years now. Never had a problem. Always there when I need them at the flick of a switch.

Just make sure you have MD axles and drive flanges at the back and MD axles, drive flanges and HD CV's upfront (i have ashcroft HD CV's)

I also added one of these to the rear diff and shaved off about 20mm from the bottom of the diff.

750001 - Arb Differential Cover Kit - Sailsbury Axle (https://www.johncraddockltd.co.uk/accessories/off-road-protection/off-road-diff-guards/750001-arb-differential-cover-kit-sailsbury-axle.html)

Cheers